The U.S. Bureau of Labor Statistics reported that the core Consumer Price Index rose 0.3% in August.
This figure exceeded economist forecasts of a 0.2% monthly increase.
Annual headline inflation remained steady at 3.4%.
Rising gasoline and shelter costs drove the monthly price gains.
The data pressures the Federal Reserve ahead of its interest rate decision next week.
Investors now price in a near-certainty of a rate hike at the upcoming meeting.
The central bank maintains a long-term inflation target of 2%.